 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.indexing;

 import java.io.FileOutputStream ;
 import java.io.IOException ;
 import java.util.Iterator ;
 import java.util.Map ;

 class LogWriter {

     protected FileOutputStream out;
     protected PageStore pageStore;

     /**
      * Puts the modified pages to the log file.
      */
     public static void putModifiedPages(PageStore pageStore, Map modifiedPages) throws PageStoreException {
         LogWriter writer = new LogWriter();
         try {
             writer.open(pageStore);
             writer.putModifiedPages(modifiedPages);
         } finally {
             writer.close();
         }
     }

     /**
      * Opens the log.
      */
     protected void open(PageStore store) throws PageStoreException {
         this.pageStore = store;
         try {
             out = new FileOutputStream (Log.name(store.getName()));
         } catch (IOException e) {
             throw new PageStoreException(PageStoreException.LogOpenFailure, e);
         }
     }

     /**
      * Closes the log.
      */
     protected void close() {
         try {
             if (out != null)
                 out.close();
         } catch (IOException e) {
             // ignore
 }
         out = null;
     }

     /**
      * Puts the modified pages into the log.
      */
     protected void putModifiedPages(Map modifiedPages) throws PageStoreException {
         Buffer b4 = new Buffer(4);
         byte[] pageBuffer = new byte[Page.SIZE];
         int numberOfPages = modifiedPages.size();
         b4.put(0, 4, numberOfPages);
         try {
             write(b4.getByteArray());
             Iterator pageStream = modifiedPages.values().iterator();
             while (pageStream.hasNext()) {
                 Page page = (Page) pageStream.next();
                 int pageNumber = page.getPageNumber();
                 b4.put(0, 4, pageNumber);
                 write(b4.getByteArray());
                 page.toBuffer(pageBuffer);
                 write(pageBuffer);
             }
         } catch (IOException e) {
             throw new PageStoreException(PageStoreException.LogWriteFailure, e);
         }
     }

     public void write(byte[] buffer) throws IOException {
         out.write(buffer);
     }

 }

